blob: fa69d5846f2fa795353b0268c03aa2e313dcf4c1 [file] [log] [blame]
Virtual environment (venv) package for Python. Based on PEP 405.
Copyright (C) 2011-2014 Vinay Sajip.
Licensed to the PSF under a contributor agreement.
import logging
import os
import shutil
import subprocess
import sys
import sysconfig
import types
CORE_VENV_DEPS = ('pip',)
logger = logging.getLogger(__name__)
class EnvBuilder:
This class exists to allow virtual environment creation to be
customized. The constructor parameters determine the builder's
behaviour when called upon to create a virtual environment.
By default, the builder makes the system (global) site-packages dir
*un*available to the created environment.
If invoked using the Python -m option, the default is to use copying
on Windows platforms but symlinks elsewhere. If instantiated some
other way, the default is to *not* use symlinks.
:param system_site_packages: If True, the system (global) site-packages
dir is available to created environments.
:param clear: If True, delete the contents of the environment directory if
it already exists, before environment creation.
:param symlinks: If True, attempt to symlink rather than copy files into
virtual environment.
:param upgrade: If True, upgrade an existing virtual environment.
:param with_pip: If True, ensure pip is installed in the virtual
:param prompt: Alternative terminal prefix for the environment.
:param upgrade_deps: Update the base venv modules to the latest on PyPI
:param scm_ignore_files: Create ignore files for the SCMs specified by the
def __init__(self, system_site_packages=False, clear=False,
symlinks=False, upgrade=False, with_pip=False, prompt=None,
upgrade_deps=False, *, scm_ignore_files=frozenset()):
self.system_site_packages = system_site_packages
self.clear = clear
self.symlinks = symlinks
self.upgrade = upgrade
self.with_pip = with_pip
self.orig_prompt = prompt
if prompt == '.': # see bpo-38901
prompt = os.path.basename(os.getcwd())
self.prompt = prompt
self.upgrade_deps = upgrade_deps
self.scm_ignore_files = frozenset(map(str.lower, scm_ignore_files))
def create(self, env_dir):
Create a virtual environment in a directory.
:param env_dir: The target directory to create an environment in.
env_dir = os.path.abspath(env_dir)
context = self.ensure_directories(env_dir)
for scm in self.scm_ignore_files:
getattr(self, f"create_{scm}_ignore_file")(context)
# See issue 24875. We need system_site_packages to be False
# until after pip is installed.
true_system_site_packages = self.system_site_packages
self.system_site_packages = False
if self.with_pip:
if not self.upgrade:
if true_system_site_packages:
# We had set it to False before, now
# restore it and rewrite the configuration
self.system_site_packages = True
if self.upgrade_deps:
def clear_directory(self, path):
for fn in os.listdir(path):
fn = os.path.join(path, fn)
if os.path.islink(fn) or os.path.isfile(fn):
elif os.path.isdir(fn):
def _venv_path(self, env_dir, name):
vars = {
'base': env_dir,
'platbase': env_dir,
'installed_base': env_dir,
'installed_platbase': env_dir,
return sysconfig.get_path(name, scheme='venv', vars=vars)
def _same_path(cls, path1, path2):
"""Check whether two paths appear the same.
Whether they refer to the same file is irrelevant; we're testing for
whether a human reader would look at the path string and easily tell
that they're the same file.
if sys.platform == 'win32':
if os.path.normcase(path1) == os.path.normcase(path2):
return True
# gh-90329: Don't display a warning for short/long names
import _winapi
path1 = _winapi.GetLongPathName(os.fsdecode(path1))
except OSError:
path2 = _winapi.GetLongPathName(os.fsdecode(path2))
except OSError:
if os.path.normcase(path1) == os.path.normcase(path2):
return True
return False
return path1 == path2
def ensure_directories(self, env_dir):
Create the directories for the environment.
Returns a context object which holds paths in the environment,
for use by subsequent logic.
def create_if_needed(d):
if not os.path.exists(d):
elif os.path.islink(d) or os.path.isfile(d):
raise ValueError('Unable to create directory %r' % d)
if os.pathsep in os.fspath(env_dir):
raise ValueError(f'Refusing to create a venv in {env_dir} because '
f'it contains the PATH separator {os.pathsep}.')
if os.path.exists(env_dir) and self.clear:
context = types.SimpleNamespace()
context.env_dir = env_dir
context.env_name = os.path.split(env_dir)[1]
context.prompt = self.prompt if self.prompt is not None else context.env_name
executable = sys._base_executable
if not executable: # see gh-96861
raise ValueError('Unable to determine path to the running '
'Python interpreter. Provide an explicit path or '
'check that your PATH environment variable is '
'correctly set.')
dirname, exename = os.path.split(os.path.abspath(executable))
if sys.platform == 'win32':
# Always create the simplest name in the venv. It will either be a
# link back to executable, or a copy of the appropriate launcher
_d = '_d' if os.path.splitext(exename)[0].endswith('_d') else ''
exename = f'python{_d}.exe'
context.executable = executable
context.python_dir = dirname
context.python_exe = exename
binpath = self._venv_path(env_dir, 'scripts')
incpath = self._venv_path(env_dir, 'include')
libpath = self._venv_path(env_dir, 'purelib')
context.inc_path = incpath
context.lib_path = libpath
# Issue 21197: create lib64 as a symlink to lib on 64-bit non-OS X POSIX
if ((sys.maxsize > 2**32) and ( == 'posix') and
(sys.platform != 'darwin')):
link_path = os.path.join(env_dir, 'lib64')
if not os.path.exists(link_path): # Issue #21643
os.symlink('lib', link_path)
context.bin_path = binpath
context.bin_name = os.path.relpath(binpath, env_dir)
context.env_exe = os.path.join(binpath, exename)
# Assign and update the command to use when launching the newly created
# environment, in case it isn't simply the executable script (e.g. bpo-45337)
context.env_exec_cmd = context.env_exe
if sys.platform == 'win32':
# bpo-45337: Fix up env_exec_cmd to account for file system redirections.
# Some redirects only apply to CreateFile and not CreateProcess
real_env_exe = os.path.realpath(context.env_exe)
if not self._same_path(real_env_exe, context.env_exe):
logger.warning('Actual environment location may have moved due to '
'redirects, links or junctions.\n'
' Requested location: "%s"\n'
' Actual location: "%s"',
context.env_exe, real_env_exe)
context.env_exec_cmd = real_env_exe
return context
def create_configuration(self, context):
Create a configuration file indicating where the environment's Python
was copied from, and whether the system site-packages should be made
available in the environment.
:param context: The information for the environment creation request
being processed.
context.cfg_path = path = os.path.join(context.env_dir, 'pyvenv.cfg')
with open(path, 'w', encoding='utf-8') as f:
f.write('home = %s\n' % context.python_dir)
if self.system_site_packages:
incl = 'true'
incl = 'false'
f.write('include-system-site-packages = %s\n' % incl)
f.write('version = %d.%d.%d\n' % sys.version_info[:3])
if self.prompt is not None:
f.write(f'prompt = {self.prompt!r}\n')
f.write('executable = %s\n' % os.path.realpath(sys.executable))
args = []
nt = == 'nt'
if nt and self.symlinks:
if not nt and not self.symlinks:
if not self.with_pip:
if self.system_site_packages:
if self.clear:
if self.upgrade:
if self.upgrade_deps:
if self.orig_prompt is not None:
if not self.scm_ignore_files:
args = ' '.join(args)
f.write(f'command = {sys.executable} -m venv {args}\n')
def symlink_or_copy(self, src, dst, relative_symlinks_ok=False):
Try symlinking a file, and if that fails, fall back to copying.
(Unused on Windows, because we can't just copy a failed symlink file: we
switch to a different set of files instead.)
assert != 'nt'
force_copy = not self.symlinks
if not force_copy:
if not os.path.islink(dst): # can't link to itself!
if relative_symlinks_ok:
assert os.path.dirname(src) == os.path.dirname(dst)
os.symlink(os.path.basename(src), dst)
os.symlink(src, dst)
except Exception: # may need to use a more specific exception
logger.warning('Unable to symlink %r to %r', src, dst)
force_copy = True
if force_copy:
shutil.copyfile(src, dst)
def create_git_ignore_file(self, context):
Create a .gitignore file in the environment directory.
The contents of the file cause the entire environment directory to be
ignored by git.
gitignore_path = os.path.join(context.env_dir, '.gitignore')
with open(gitignore_path, 'w', encoding='utf-8') as file:
file.write('# Created by venv; '
if != 'nt':
def setup_python(self, context):
Set up a Python executable in the environment.
:param context: The information for the environment creation request
being processed.
binpath = context.bin_path
path = context.env_exe
copier = self.symlink_or_copy
dirname = context.python_dir
copier(context.executable, path)
if not os.path.islink(path):
os.chmod(path, 0o755)
for suffix in ('python', 'python3',
path = os.path.join(binpath, suffix)
if not os.path.exists(path):
# Issue 18807: make copies if
# symlinks are not wanted
copier(context.env_exe, path, relative_symlinks_ok=True)
if not os.path.islink(path):
os.chmod(path, 0o755)
def setup_python(self, context):
Set up a Python executable in the environment.
:param context: The information for the environment creation request
being processed.
binpath = context.bin_path
dirname = context.python_dir
exename = os.path.basename(context.env_exe)
exe_stem = os.path.splitext(exename)[0]
exe_d = '_d' if os.path.normcase(exe_stem).endswith('_d') else ''
if sysconfig.is_python_build():
scripts = dirname
scripts = os.path.join(os.path.dirname(__file__),
'scripts', 'nt')
if not sysconfig.get_config_var("Py_GIL_DISABLED"):
python_exe = os.path.join(dirname, f'python{exe_d}.exe')
pythonw_exe = os.path.join(dirname, f'pythonw{exe_d}.exe')
link_sources = {
'python.exe': python_exe,
f'python{exe_d}.exe': python_exe,
'pythonw.exe': pythonw_exe,
f'pythonw{exe_d}.exe': pythonw_exe,
python_exe = os.path.join(scripts, f'venvlauncher{exe_d}.exe')
pythonw_exe = os.path.join(scripts, f'venvwlauncher{exe_d}.exe')
copy_sources = {
'python.exe': python_exe,
f'python{exe_d}.exe': python_exe,
'pythonw.exe': pythonw_exe,
f'pythonw{exe_d}.exe': pythonw_exe,
exe_t = f'3.{sys.version_info[1]}t'
python_exe = os.path.join(dirname, f'python{exe_t}{exe_d}.exe')
pythonw_exe = os.path.join(dirname, f'pythonw{exe_t}{exe_d}.exe')
link_sources = {
'python.exe': python_exe,
f'python{exe_d}.exe': python_exe,
f'python{exe_t}.exe': python_exe,
f'python{exe_t}{exe_d}.exe': python_exe,
'pythonw.exe': pythonw_exe,
f'pythonw{exe_d}.exe': pythonw_exe,
f'pythonw{exe_t}.exe': pythonw_exe,
f'pythonw{exe_t}{exe_d}.exe': pythonw_exe,
python_exe = os.path.join(scripts, f'venvlaunchert{exe_d}.exe')
pythonw_exe = os.path.join(scripts, f'venvwlaunchert{exe_d}.exe')
copy_sources = {
'python.exe': python_exe,
f'python{exe_d}.exe': python_exe,
f'python{exe_t}.exe': python_exe,
f'python{exe_t}{exe_d}.exe': python_exe,
'pythonw.exe': pythonw_exe,
f'pythonw{exe_d}.exe': pythonw_exe,
f'pythonw{exe_t}.exe': pythonw_exe,
f'pythonw{exe_t}{exe_d}.exe': pythonw_exe,
do_copies = True
if self.symlinks:
do_copies = False
# For symlinking, we need all the DLLs to be available alongside
# the executables.
f: os.path.join(dirname, f) for f in os.listdir(dirname)
if os.path.normcase(f).startswith(('python', 'vcruntime'))
and os.path.normcase(os.path.splitext(f)[1]) == '.dll'
to_unlink = []
for dest, src in link_sources.items():
dest = os.path.join(binpath, dest)
os.symlink(src, dest)
except OSError:
logger.warning('Unable to symlink %r to %r', src, dst)
do_copies = True
for f in to_unlink:
except OSError:
logger.warning('Failed to clean up symlink %r',
logger.warning('Retrying with copies')
if do_copies:
for dest, src in copy_sources.items():
dest = os.path.join(binpath, dest)
shutil.copy2(src, dest)
except OSError:
logger.warning('Unable to copy %r to %r', src, dest)
if sysconfig.is_python_build():
# copy init.tcl
for root, dirs, files in os.walk(context.python_dir):
if 'init.tcl' in files:
tcldir = os.path.basename(root)
tcldir = os.path.join(context.env_dir, 'Lib', tcldir)
if not os.path.exists(tcldir):
src = os.path.join(root, 'init.tcl')
dst = os.path.join(tcldir, 'init.tcl')
shutil.copyfile(src, dst)
def _call_new_python(self, context, *py_args, **kwargs):
"""Executes the newly created Python using safe-ish options"""
# gh-98251: We do not want to just use '-I' because that masks
# legitimate user preferences (such as not writing bytecode). All we
# really need is to ensure that the path variables do not overrule
# normal venv handling.
args = [context.env_exec_cmd, *py_args]
kwargs['env'] = env = os.environ.copy()
env['VIRTUAL_ENV'] = context.env_dir
env.pop('PYTHONHOME', None)
env.pop('PYTHONPATH', None)
kwargs['cwd'] = context.env_dir
kwargs['executable'] = context.env_exec_cmd
subprocess.check_output(args, **kwargs)
def _setup_pip(self, context):
"""Installs or upgrades pip in a virtual environment"""
self._call_new_python(context, '-m', 'ensurepip', '--upgrade',
'--default-pip', stderr=subprocess.STDOUT)
def setup_scripts(self, context):
Set up scripts into the created environment from a directory.
This method installs the default scripts into the environment
being created. You can prevent the default installation by overriding
this method if you really need to, or if you need to specify
a different location for the scripts to install. By default, the
'scripts' directory in the venv package is used as the source of
scripts to install.
path = os.path.abspath(os.path.dirname(__file__))
path = os.path.join(path, 'scripts')
self.install_scripts(context, path)
def post_setup(self, context):
Hook for post-setup modification of the venv. Subclasses may install
additional packages or scripts here, add activation shell scripts, etc.
:param context: The information for the environment creation request
being processed.
def replace_variables(self, text, context):
Replace variable placeholders in script text with context-specific
Return the text passed in , but with variables replaced.
:param text: The text in which to replace placeholder variables.
:param context: The information for the environment creation request
being processed.
text = text.replace('__VENV_DIR__', context.env_dir)
text = text.replace('__VENV_NAME__', context.env_name)
text = text.replace('__VENV_PROMPT__', context.prompt)
text = text.replace('__VENV_BIN_NAME__', context.bin_name)
text = text.replace('__VENV_PYTHON__', context.env_exe)
return text
def install_scripts(self, context, path):
Install scripts into the created environment from a directory.
:param context: The information for the environment creation request
being processed.
:param path: Absolute pathname of a directory containing script.
Scripts in the 'common' subdirectory of this directory,
and those in the directory named for the platform
being run on, are installed in the created environment.
Placeholder variables are replaced with environment-
specific values.
binpath = context.bin_path
plen = len(path)
if == 'nt':
def skip_file(f):
f = os.path.normcase(f)
return (f.startswith(('python', 'venv'))
and f.endswith(('.exe', '.pdb')))
def skip_file(f):
return False
for root, dirs, files in os.walk(path):
if root == path: # at top-level, remove irrelevant dirs
for d in dirs[:]:
if d not in ('common',
continue # ignore files in top level
for f in files:
if skip_file(f):
srcfile = os.path.join(root, f)
suffix = root[plen:].split(os.sep)[2:]
if not suffix:
dstdir = binpath
dstdir = os.path.join(binpath, *suffix)
if not os.path.exists(dstdir):
dstfile = os.path.join(dstdir, f)
if == 'nt' and srcfile.endswith(('.exe', '.pdb')):
shutil.copy2(srcfile, dstfile)
with open(srcfile, 'rb') as f:
data =
new_data = (
self.replace_variables(data.decode('utf-8'), context)
except UnicodeError as e:
logger.warning('unable to copy script %r, '
'may be binary: %s', srcfile, e)
if new_data == data:
shutil.copy2(srcfile, dstfile)
with open(dstfile, 'wb') as f:
shutil.copymode(srcfile, dstfile)
def upgrade_dependencies(self, context):
f'Upgrading {CORE_VENV_DEPS} packages in {context.bin_path}'
self._call_new_python(context, '-m', 'pip', 'install', '--upgrade',
def create(env_dir, system_site_packages=False, clear=False,
symlinks=False, with_pip=False, prompt=None, upgrade_deps=False,
*, scm_ignore_files=frozenset()):
"""Create a virtual environment in a directory."""
builder = EnvBuilder(system_site_packages=system_site_packages,
clear=clear, symlinks=symlinks, with_pip=with_pip,
prompt=prompt, upgrade_deps=upgrade_deps,
def main(args=None):
import argparse
parser = argparse.ArgumentParser(prog=__name__,
description='Creates virtual Python '
'environments in one or '
'more target '
epilog='Once an environment has been '
'created, you may wish to '
'activate it, e.g. by '
'sourcing an activate script '
'in its bin directory.')
parser.add_argument('dirs', metavar='ENV_DIR', nargs='+',
help='A directory to create the environment in.')
parser.add_argument('--system-site-packages', default=False,
action='store_true', dest='system_site',
help='Give the virtual environment access to the '
'system site-packages dir.')
if == 'nt':
use_symlinks = False
use_symlinks = True
group = parser.add_mutually_exclusive_group()
group.add_argument('--symlinks', default=use_symlinks,
action='store_true', dest='symlinks',
help='Try to use symlinks rather than copies, '
'when symlinks are not the default for '
'the platform.')
group.add_argument('--copies', default=not use_symlinks,
action='store_false', dest='symlinks',
help='Try to use copies rather than symlinks, '
'even when symlinks are the default for '
'the platform.')
parser.add_argument('--clear', default=False, action='store_true',
dest='clear', help='Delete the contents of the '
'environment directory if it '
'already exists, before '
'environment creation.')
parser.add_argument('--upgrade', default=False, action='store_true',
dest='upgrade', help='Upgrade the environment '
'directory to use this version '
'of Python, assuming Python '
'has been upgraded in-place.')
parser.add_argument('--without-pip', dest='with_pip',
default=True, action='store_false',
help='Skips installing or upgrading pip in the '
'virtual environment (pip is bootstrapped '
'by default)')
help='Provides an alternative prompt prefix for '
'this environment.')
parser.add_argument('--upgrade-deps', default=False, action='store_true',
help=f'Upgrade core dependencies ({", ".join(CORE_VENV_DEPS)}) '
'to the latest version in PyPI')
parser.add_argument('--without-scm-ignore-files', dest='scm_ignore_files',
action='store_const', const=frozenset(),
help='Skips adding SCM ignore files to the environment '
'directory (Git is supported by default).')
options = parser.parse_args(args)
if options.upgrade and options.clear:
raise ValueError('you cannot supply --upgrade and --clear together.')
builder = EnvBuilder(system_site_packages=options.system_site,
for d in options.dirs:
if __name__ == '__main__':
rc = 1
rc = 0
except Exception as e:
print('Error: %s' % e, file=sys.stderr)